1. Field of the Invention
This invention concerns a method and material for sealing joints in horizontal surfaces, at least one side of the joint being asphalt.
2. Background Information
Asphalt roadway surfaces, either on an asphalt pavement structure or an asphalt overlay, are subjected to cracking due to thermal stresses. The cracks can be due to the stresses in the pavement structure itself, in the asphalt overlay itself, or due to stresses in the overlay due to movement of the underlying pavement structure. In any case, these cracks must be sealed in order to prevent the intrusion of water and solid debris, which will further damage the asphalt roadway. Many concrete roadway surfaces have an asphalt shoulder along side the outer edge. The joint between the concrete and the asphalt must be sealed in order to prevent the intrusion of water and solid debris.
The traditional method of sealing has been to fill the cracks with hot applied bituminous based sealants. These work in a non-moving cracks, but not in those that move, such as the reflection cracks over an expansion joint in a pavement structure. This invention is addressed to solving the problem of sealing working cracks in asphalt roadways and shoulders.
A cold applied joint sealant usable for both portland cement and asphaltic concrete pavements is taught in U.S. Pat. No. 4,443,578 issued April 17, 1984. The formulation comprises asphalt, plasticising oil, inorganic filler, anti-settling agent, hydroxyl terminated liquid poluybutadiene resin, aromatic solvent, urethane catalyst, and polymeric isocyanate. The sealant provides an initial set in about 120 minutes, 300 percent extension at -22.degree. F. and a penetration value of 125 to 145 at 77.degree. F. and 35-55 at 0.degree. F.
U.S. Pat. No. 3,766,127, issued Oct. 16, 1973, teaches a low modulus room temperature vulcanizable silicone elastomer. The composition is based upon an acetamido containing chain extender and crosslinker in combination with a hydroxyl endblocked polydiorganosiloxane. When fillers are used in the composition it is useful as a sealant.
U.S. Pat. No. 3,817,909, issued June 18, 1974, teaches a low modulus room temperature vulcanizable silicone elastomer is obtained by mixing a hydroxyl endblocked polydiorganosiloxane, non-acidic, non-reinforcing filler, acetamido containing chain extender and crosslinker which is an aminoxysilicon compound having 3 to 10 aminoxy groups per molecule. The sealant is useful in building construction.
U.S. Pat. No. 3,996,184, issued Dec. 7, 1976, teaches a one package, low modulus, room temperature vulcanizable silicone elastomer composition having improved slump characteristics at low temperatures. This composition is obtained by mixing a hydroxyl endblocked polydimethylsiloxane, non-acidic, non-reinforcing filler, methylvinyldi-(N-acetamido)silane, an aminoxysilicon compound having 3 to 10 aminoxy groups per molecule, and a diluent selected from N,N-dimethyl-formamide, acetonitrile, or N-n-butylacetamide. The elastomer is useful in building construction.
Materials such as discussed above have been used as highway sealants. Such materials have served very well, but they are difficult to apply because they must be extruded into the joint and then tooled to obtain a good seal to the concrete sides of the joint, since the sealants are not self-leveling. They do not perform in a joint where at least one of the sides is asphalt.